AHSG: Adversarial Attacks on High-level Semantics in Graph Neural Networks

Graph Neural Networks (GNNs) have garnered significant interest among researchers due to their impressive performance in graph learning tasks. However, like other deep neural networks, GNNs are also vulnerable to adversarial attacks. In existing adversarial attack methods for GNNs, the metric between the attacked graph and the original graph is usually the attack budget or a measure of global graph properties. However, we have found that it is possible to generate attack graphs that disrupt the primary semantics even within these constraints. To address this problem, we propose a Adversarial Attacks on High-level Semantics in Graph Neural Networks (AHSG), which is a graph structure attack model that ensures the retention of primary semantics. The latent representations of each node can extract rich semantic information by applying convolutional operations on graph data. These representations contain both task-relevant primary semantic information and task-irrelevant secondary semantic information. The latent representations of same-class nodes with the same primary semantics can fulfill the objective of modifying secondary semantics while preserving the primary semantics. Finally, the latent representations with attack effects is mapped to an attack graph using Projected Gradient Descent (PGD) algorithm. By attacking graph deep learning models with some advanced defense strategies, we validate that AHSG has superior attack effectiveness compared to other attack methods. Additionally, we employ Contextual Stochastic Block Models (CSBMs) as a proxy for the primary semantics to detect the attacked graph, confirming that AHSG almost does not disrupt the original primary semantics of the graph.